In a military defense of a geographic zone, it is known to utilize explosive mines, and other pre-positioned ordnance, to automatically attack enemy intruders without human direction. It is also known to use pre-positioned sensors, lights, alarms and other devices to perform additional defensive actions such as enemy detection and illumination. After the defensive devices are geographically deployed, it is desirable to be able to communicate information from a nearby or more remote location to the devices and to selectively control their status or actions. Electromagnetic waves may be used for such communication but may be limited by problems of communication security and requirements for specialized receivers at each of the devices. Seismic waves or acoustic waves have also been proposed as a means of such communication for both on and offshore mines, as in U.S. Pat. No. 5,125,317 by Moshe Spektor et al and U.S. Patent Application Publication No. 2002/0170419. However, the approaches so far described have been limited in versatility, distance of communication and reliability. One significant limitation of such prior art seismic communication methods is that only a very limited range of information, actions or commands may be communicated.